The Data Coordinating Center (DCC) for the African American Study of Kidney Disease and Hypertension (AASK) Full-Scale Trial will coordinate the scientific and operational aspects of the Study. This Study will examine the effectiveness of three stepped-care regimens in lowering blood pressure and two levels of blood pressure control in African Americans with hypertensive renal disease in order to slow the loss of kidney function as measured by glomerular filtration rate. In the transition months of the Recruitment Phase (Phase I), the DCC will review the Pilot Study data and protocol in conjunction with the Steering Committee to finalize the design of the Full-Scale Trial. Systems for data acquisition (via distributed data entry) and data management (using Oracle) will be established. A major activity of the DCC will be the development of procedures for control of the quality of the data. Review and finalization of the Manual of Operations and data forms will be done. The randomization schedule for entering patients will be generated. Central facilities at the Cleveland Clinic will be established for the measurement of renal function and biochemistry along with a Drug Distribution Center to coordinate the distribution of antihypertensive medications. The DCC will provide centralized training of Clinical Center staff in the areas of entry of study subjects, completion of study forms, use of the distributed data entry system and testing of renal function. The DCC will arrange meetings of the Steering Committee and participate in these meetings and report the proceedings. The database management system developed in Phase I will be used to assure accurate and complete collection of study data. A query system will be used to resolve data discrepancies. A major function of the DCC during the Recruitment Phase (Phase I) of the study will be to monitor patient recruitment and compliance as a whole and by Clinical Center. Study progress will be reported in monthly reports to the Clinical Centers, newsletters, and presentations at the Steering Committee, and Data and Safety Monitoring Board meetings. Statistical analyses will be performed during the course of the study with final analyses completed and reported during Phase III of the study. The DCC will develop new statistical methodology as needed to properly analyze the data being collected. Since the Study is a multi-centered effort including several organizational components, the DCC will be proactive in performing its duties so that the goals of the study are met. The DCC will work to foster a spirit of cooperation which is important in this multi-center study.